Distribution of radiation induced defects and modification of optical constants of GaAs implanted with high energy 56Fe ions

Single crystal GaAs substrates implanted with high-energy Fe-56 ions have been optically investigated before and after annealing, over the photon energy range 0.1-1.4eV. The spatial distribution of the damage has been probed by etching the sample and shows that defect density peaks at a depth of about 10 mum. Annealing studies show that the mid gap defect states are annealed out more rapidly than the near band edge defect states during annealing up to 350degreesC whereas the near band edge defect states are annealed out more rapidly than mid gap defect states during annealing between 350-600degreesC. The fringe patterns observed in the transmission spectra have been analyzed to investigate quantitatively changes in the refractive index of the radiation-dam aged region. Kramers-Kronig relation has been used to correlate the absorption due to damage with changes in the refractive index. The results show that the high-energy ion-implanted layer contained amorphous pockets. (C) 2004 Elsevier B.V. All rights reserved.